1. Field of the Invention
This invention relates to linear, saturated polyester blends having improved impact properties. The blends contain an impact modifying amount of a combination of an acrylate-containing core-shell polymer and a copolymer of an alpha-olefin having 2 to 8 carbon atoms and a monomer selected from an unsaturated carboxylic acid having 3 to 8 carbon atoms and its derivatives including salts, anhydrides and the like. Also included are graft polymers.
2. Description of the Prior Art
It is known in the art that linear, saturated polyesters such as linear, saturated polyesters of aromatic dicarboxylic acids can be improved with respect to impact properties. It is known, for example, that the impact property of such polyesters can be improved by blending with the polyester an amount of certain core-shell polymers. Such core-shell polymers are in the form of small particles in which the core has an elastomeric character and the shell is of a substantially rigid thermoplastic character. Also, blends of such polyesters are known in which the impact has been improved by blending therewith an amount of carboxylic acid-containing copolymers of alpha-olefins having 2 to 8 carbon atoms and a monomer selected from an unsaturated carboxylic acid having 3 to 8 carbon atoms and its derivatives, such as ethylene-acrylic acid or ethylene-methacrylic acid copolymers. It is known in the art, additionally, that impact strength of polyesters can be improved to some degree by the incorporation of certain elastomers such as polybutadiene, butadiene-styrene rubbery copolymers, butadiene-acrylonitrile rubbery copolymers, ethylene-propylene rubbery copolymers, polyisobutene and polyisoprene.
It is desired that by the improvement of impact values of the polyester blends there will be a relatively small loss, if any, of other desired properties of polyester blends. For example, it is desired that the melt viscosity of the polyester not be greatly increased by the incorporation of impact modifiers in amounts necessary to significantly enhance the impact values.